<?php
namespace TYPO3\CMS\Fluid\Core\ViewHelper;

/*                                                                        *
 * This script is backported from the TYPO3 Flow package "TYPO3.Fluid".   *
 *                                                                        *
 * It is free software; you can redistribute it and/or modify it under    *
 * the terms of the GNU Lesser General Public License, either version 3   *
 *  of the License, or (at your option) any later version.                *
 *                                                                        *
 *                                                                        *
 * This script is distributed in the hope that it will be useful, but     *
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHAN-    *
 * TABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser       *
 * General Public License for more details.                               *
 *                                                                        *
 * You should have received a copy of the GNU Lesser General Public       *
 * License along with the script.                                         *
 * If not, see http://www.gnu.org/licenses/lgpl.html                      *
 *                                                                        *
 * The TYPO3 project - inspiring people to share!                         *
 *                                                                        */
/**
 * Arguments list. Wraps an array, but only allows read-only methods on it.
 * Is available inside every view helper as $this->arguments - and you use it as if it was an array.
 * However, you can only read, and not write to it.
 *
 * @api
 */
class Arguments implements \ArrayAccess
{
    /**
     * @var array the arguments themselves
     */
    protected $arguments = array();

    /**
     * Constructor.
     *
     * @param array $arguments Array of arguments
     * @api
     */
    public function __construct(array $arguments)
    {
        $this->arguments = $arguments;
    }

    /**
     * Checks if a given key exists in the array
     *
     * @param string $key Key to check
     * @return bool true if exists
     */
    public function offsetExists($key)
    {
        return array_key_exists($key, $this->arguments);
    }

    /**
     * Returns the value to the given key.
     *
     * @param string $key Key to get.
     * @return object associated value
     */
    public function offsetGet($key)
    {
        if (!array_key_exists($key, $this->arguments)) {
            return null;
        }
        return $this->arguments[$key];
    }

    /**
     * Throw exception if you try to set a value.
     *
     * @param string $key
     * @param object $value
     */
    public function offsetSet($key, $value)
    {
        throw new \TYPO3\CMS\Fluid\Core\Exception('Tried to set argument "' . $key . '", but setting arguments is forbidden.', 1236080693);
    }

    /**
     * Throw exception if you try to unset a value.
     *
     * @param string $key
     */
    public function offsetUnset($key)
    {
        throw new \TYPO3\CMS\Fluid\Core\Exception('Tried to unset argument "' . $key . '", but setting arguments is forbidden.', 1236080702);
    }

    /**
     * Checks if an argument with the specified name exists
     *
     * @param string $argumentName Name of the argument to check for
     * @return bool TRUE if such an argument exists, otherwise FALSE
     * @see offsetExists()
     */
    public function hasArgument($argumentName)
    {
        return $this->offsetExists($argumentName) && $this->arguments[$argumentName] !== null;
    }
}
